DE4A Connector
Introduction
The DE4A Connector is a technical proxy that allows the final participants (DE or DO) to send requests for evidence or responses to other final participants over an eDelivery communication environment. In addition, to handle the message exchange process, the Connector is responsible for obtaining the message routing information, by exchanging information with external components such as the IDK, the SML/DNS or the SMP.
To do so, it provides a common interface to DEs and DOs, making the complexity of the system transparent to the final participants and integration easier.
The Connector component provides the AS4 Gateway functionality, so it can assume both the role of Data Requestor and Data Transferor. This first approach makes the Connector a stand-alone web application that can be deployed on any suitable application server. As an alternative, the Connector can make used of an external AS4 Gateway to provide the message exchange feature, in which case two components should be deployed: the DE4A Connector along with the chosen AS4 Gateway (i.e. Domibus).
The security and integrity of messages, as well as the unique identification of the participants involved, are the cornerstones of the Connector component.
Functionalities provided
The main purpose of the DE4A Connector is sending and receiving of evidence requests and their responses. The message exchange process is described in the DE4A deliverables D2.4 Project Start Architecture and D5.3 Initial technical design of interfaces.
Routing information lookup
The Connector is responsible for obtaining the Data Provider information from the IDK. It exposes a REST API /lookupRoutingInformation to get information about the Data Owners that provide a specific Canonical Evidence Type and further related information. That information is used to construct a request message to be sent through the Connector. Thus, the Data Evaluator is the only consumer of the mentioned API method.
Dynamic discovery of Services
In order for the Connector to be able to send a message to the corresponding endpoint, the eDelivery dynamic discovery mode of operation is used. This operation mode is based on the use of the SML/DNS and SMP components of the eDelivery infrastructure. The main elements stored in the SML/DNS and SMPs for this purpose are the following:
- ParticipantIdentifier: The Data Owner/Data Evaluator identifier who is publishing its AS4 communication point (of the Connector linked to it).
- DocumentTypeIdentifier: Canonical evidence type.
- ProcessIdentifier: Orchestration type (request/response).
- AS4 endpoint: AS4 service endpoint URL.
- Certificate: The X.509 certificate of the AS4 server, used to encrypt the transmitted data for this specific participant.
The information described above is managed by the SML/DNS and SMP components and is used by the Connector when working with the phase4 implementation of AS4. In cases where the Connector runs with external AS4 implementations such as Domibus, the end-to-end AS4 communication will be handled by the configuration of that external platform.
Focusing on the SML/DNS/SMP data retrieval, the process will take place according to the following features:
- SSL/TLS communication is mandatory.
- Response signature validation is mandatory.
- The communication between SMP and SML requires the usage of a client certificate.
The service metadata lookup will be performed as a step prior to the AS4 message exchange. Therefore, the participant IDs and other related information must be known by the Connector in advance.